JP6591223B2 - Fixed constant velocity universal joint - Google Patents

Description

  The present invention is used in power transmission systems of automobiles, aircraft, ships, and various industrial machines. Specifically, for example, it is incorporated in a drive shaft or a propeller shaft used in an FF vehicle, a 4WD vehicle, etc. The present invention relates to a fixed type constant velocity universal joint that allows only displacement.

  Referring to FIG. 1, the Rzeppa type constant velocity universal joint as fixed constant velocity universal joint 1 mainly includes an outer joint member 2, an inner joint member 3, a ball 4 and a cage 5. A plurality of curved track grooves 6 are formed on the spherical inner peripheral surface 8 of the outer joint member 2 at equal intervals in the circumferential direction and along the axial direction. A plurality of curved track grooves 7 facing the track grooves 6 of the outer joint member 2 are formed on the spherical outer peripheral surface 9 of the inner joint member 3 at equal intervals in the circumferential direction and along the axial direction. A plurality of balls 4 for transmitting torque are incorporated one by one between the track groove 6 of the outer joint member 2 and the track groove 7 of the inner joint member 3. A cage 5 that holds the ball 4 is disposed between the spherical inner peripheral surface 8 of the outer joint member 2 and the spherical outer peripheral surface 9 of the inner joint member 3. The outer periphery of the outer joint member 2 and the outer periphery of the shaft 12 connected to the inner joint member 3 are covered with a boot 13, and grease is enclosed as a lubricant inside the joint.

  The centers of curvature of the spherical inner peripheral surface 8 of the outer joint member 2 and the spherical outer peripheral surface 9 of the inner joint member 3 are both formed at the center O of the joint. In contrast, the center of curvature A of the track groove 6 of the outer joint member 2 and the center of curvature B of the track groove 7 of the inner joint member 3 are offset by an equal distance f1 on the opposite side in the axial direction with respect to the center O of the joint. ing. As a result, when the joint takes an operating angle, the ball 4 is always guided on a plane that bisects the angle formed by the two axes of the outer joint member 2 and the inner joint member 3, and rotates at a constant speed between the two axes. Torque is transmitted.

  The fixed type constant velocity universal joint 1 is an 8-ball type Rzeppa type constant velocity universal joint. Compared with the conventional constant velocity universal joint of 6 balls, the track offset amount f1 is reduced and the number of balls is increased. In addition, by reducing the diameter, the strength, load capacity and durability of the fixed constant velocity universal joint using six balls are equal to or higher than that of the fixed type. A universal joint has been realized. The axial clearance (hereinafter referred to as pocket clearance) between the pocket of the cage of the fixed type constant velocity universal joint and the ball (hereinafter referred to as pocket clearance) is an intermediate fit or a tight fit as described in Patent Document 1. Set to fit. This is because when the negative clearance is excessive, smooth movement of the ball is inhibited, and when the positive clearance is excessive, abnormal noise (ball hitting sound) is generated.

JP 2006-5186 A

  The torque loss of the constant velocity universal joint used for the drive shaft is relatively small among the drive system parts of the automobile, and the ratio of the torque loss to the input torque has reached 1% or less. For this reason, automakers have been trying to improve efficiency from components such as transmissions that have a relatively large torque loss, but in recent years, competition for lower fuel consumption has intensified, and constant velocity universal joints are required to further reduce torque loss. It became so.

  In order to respond to the demands of such automobile manufacturers, various pocket clearance samples are manufactured, and by making the pocket clearance correct, the movement of the ball becomes smooth and the torque loss rate is reduced. Confirmed by experiment. On the other hand, in the acoustic test, when the positive clearance was increased, ball hitting sound was confirmed in a region where the operating angle of the joint was large. Details of the contents confirmed by the experiment will be described later.

  The present invention has been proposed in view of the problems identified in the above-described experiment, and the purpose thereof is to prevent abnormal noise (ball hitting sound) from occurring in a region where the operating angle of the joint is large, and to be used regularly. The corner is to realize a fixed type constant velocity universal joint with low torque loss.

In order to achieve the above-mentioned object, the present inventors have arrived at the present invention through the following verification and inference activities, which will be described later in detail.
(1) Verification of transmission efficiency at normal angle (2) Verification of abnormal noise at high operating angle range (3) Analysis of generation mechanism of abnormal noise (4) Analysis of movement trajectory of ball in pocket (5) New idea

As technical means for achieving the above-mentioned object, the present invention includes an outer joint member in which a plurality of curved track grooves extending in the axial direction are formed on the spherical inner peripheral surface, and an axial extension on the spherical outer peripheral surface. An inner joint member formed with a plurality of curved track grooves, a plurality of torque transmission balls disposed between the track grooves of the outer joint member and the track grooves of the inner joint member corresponding thereto, A retainer having a spherical outer peripheral surface and a spherical inner peripheral surface that hold the torque transmitting ball in a pocket and fit to the spherical inner peripheral surface of the outer joint member and the spherical outer peripheral surface of the inner joint member, respectively, In a fixed type constant velocity universal joint in which the center of curvature of the curved track groove of the joint member and the center of curvature of the curved track groove of the inner joint member are offset equidistantly in the axial direction opposite to the joint center Of the pair of pocket side surfaces facing in the axial direction of said pocket, a recess is formed in the center portion of the circumferential direction of the at least one pocket side, this recess includes a moving track of the torque transmitting balls in the regular angle, said Of the initial pocket clearance between the cage pocket and the torque transmission ball, the initial pocket clearance in the ball movement region at the service angle is set in the recess, and the space between the pocket of the cage and the torque transmission ball is set. The initial pocket clearance is up to a positive clearance in the ball movement region at the normal angle, and is a negative clearance in a region other than the ball movement region at the normal angle.

With the above configuration, it is possible to realize a fixed type constant velocity universal joint in which abnormal noise (ball hitting sound) does not occur in a region where the operating angle of the joint is large, and torque loss is small at a normal angle. As a more specific effect, idling vibration can be improved by reducing the bending torque, and the movement of the ball is smoothed and the frictional force is reduced, so that heat generation during joint operation is reduced and the durability life is improved. In particular, a concave portion is formed in the central portion in the circumferential direction of at least one of the pair of pocket side surfaces facing the axial direction of the pocket, and the concave portion includes the movement trajectory of the torque transmitting ball at a normal angle. By doing so, the initial pocket clearance can be reliably set to the correct clearance in the ball movement region at the normal angle. In addition, the concave portion can be formed by machining such as cutting or grinding, cold plastic working, electric discharge machining, or the like.

  It is preferable to include the movement trajectory of the ball when the joint operates at a normal angle by forming the concave portion in a belt shape in the circumferential direction of the cage. Thereby, the initial pocket clearance can be set to the correct clearance with high processing efficiency.

  It is preferable that the concave portion is formed in a band shape in the radial direction of the cage and extends from the spherical inner peripheral surface of the cage to the spherical outer peripheral surface. Thereby, a recessed part can be shape | molded simultaneously at the time of the shaving process of a pocket side surface, productivity is good, and manufacturing cost can be suppressed.

  By making the cross-sectional shape of the concave portion into an arc shape, or by forming it from a tapered surface, it is possible to smoothly connect the ball movement region at the normal angle and the region other than this region.

  By forming the pocket side surface as a concave surface in the cross section of the cage, the entire pocket side surface can be processed at one time by mechanical processing such as cutting or grinding, cold plastic processing or electric discharge processing.

  By making the cross-sectional shape of the concave surface into an arc shape or comprising a tapered surface, it is possible to smooth the change in the amount of pocket clearance between the ball movement region at the normal angle and the region other than this region. .

  According to the present invention, it is possible to realize a fixed type constant velocity universal joint in which abnormal noise (ball hitting sound) does not occur in a region where the operating angle of the joint is large and torque loss is small at a normal angle. As a more specific effect, idling vibration can be improved by reducing the bending torque, and the movement of the ball is smoothed and the frictional force is reduced, so that heat generation during joint operation is reduced and the durability life is improved.

It is a fragmentary longitudinal cross-sectional view of the fixed type constant velocity universal joint of 1st Embodiment which concerns on this invention. FIG. 2 is a cross-sectional view of a fixed type constant velocity universal joint taken along the line P-P in FIG. 1. FIG. 3 is an enlarged cross-sectional view of a ball and a track groove in FIG. 2. It is a graph which shows the knowledge about the relationship between a pocket clearance amount and a torque loss rate. It is a graph which shows the knowledge about the relationship between the amount of pocket clearances, and the audible distance of unusual sound. (A) A figure is a longitudinal cross-sectional view which shows the state which the joint took the big operating angle, (b) A figure is a schematic diagram explaining the force with which a ball | bowl presses a cage | basket. It is a graph which shows the pocket load during one rotation of a joint. It is a schematic diagram which shows a pocket clearance and a motion of a ball | bowl. It is a schematic diagram which shows the movement locus | trajectory of the ball | bowl in a pocket. (A) The figure is a front view of the cage alone, and (b) is a perspective view. FIG. 10A is a cross-sectional view taken along line GG in FIG. 10A, FIG. 10B is an enlarged view of a portion I in FIG. 10A, and FIG. b) It is the fragmentary sectional view which looked at the JJ line | wire of the figure. (A) The figure is the longitudinal cross-sectional view which looked at the KK line | wire of FIG. 10 (a), (b) The figure-(e) figure are the enlarged views of the L section in (a) figure, and a pocket side surface. Various forms of recesses are shown. (A) The figure is a cross-sectional view taken along the line G-G in FIG. (B) The figure is an enlarged view of the I section in (a) figure, and (c) figure is the fragmentary sectional view which looked at the JJ line of (b) figure. The other modification of the recessed part of a pocket side surface is shown, (a) figure is an enlarged view of the I section in Fig.13 (a), (b) figure was seen by the JJ line | wire of (a) figure. It is a fragmentary sectional view. It is a longitudinal cross-sectional view of the fixed type constant velocity universal joint which concerns on 2nd Embodiment. FIG. 16 is a side view taken along the line MM in FIG. 15. It is a longitudinal cross-sectional view of the fixed type constant velocity universal joint which concerns on 3rd Embodiment.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. First, the whole structure of the fixed type constant velocity universal joint of this embodiment is demonstrated based on FIGS. 1 is a partial longitudinal sectional view of a fixed type constant velocity universal joint according to the present embodiment, FIG. 2 is a transverse sectional view taken along the line PP in FIG. 1, and FIG. 3 is an enlarged view of a ball and a track groove. It is a cross-sectional view.

  The fixed type constant velocity universal joint 1 of the present embodiment is a Rzeppa type constant velocity universal joint, and as shown in FIGS. 1 and 2, an outer joint member 2, an inner joint member 3, a torque transmission ball 4 (hereinafter simply referred to as a “joint velocity constant universal joint”). Ball) and the cage 5 are the main components. Eight curved track grooves 6 are formed on the spherical inner peripheral surface 8 of the outer joint member 2 at equal intervals in the circumferential direction and along the axial direction. Eight curved track grooves 7 facing the track grooves 6 of the outer joint member 2 are formed on the spherical outer peripheral surface 9 of the inner joint member 3 at equal intervals in the circumferential direction and along the axial direction. . Eight balls 4 for transmitting torque are incorporated one by one between the track groove 6 of the outer joint member 2 and the track groove 7 of the inner joint member 3. A cage 5 that holds the ball 4 is disposed between the spherical inner peripheral surface 8 of the outer joint member 2 and the spherical outer peripheral surface 9 of the inner joint member 3. The spherical outer circumferential surface 10 of the cage 5 is fitted with the spherical inner circumferential surface 8 of the outer joint member 2, and the spherical inner circumferential surface 11 of the cage 5 is fitted with the spherical outer circumferential surface 9 of the inner joint member 3.

  The centers of curvature of the spherical inner peripheral surface 8 of the outer joint member 2 and the spherical outer peripheral surface 9 of the inner joint member 3 are respectively formed at the center O of the joint. On the other hand, the center of curvature A of the curved track groove 6 of the outer joint member 2 and the center of curvature B of the curved track groove 7 of the inner joint member 3 are opposite to the center O of the joint in the axial direction. Is offset by the same distance f1. Thus, when the joint takes an operating angle, the ball 4 is always guided on a plane that bisects the angle formed by the two axes of the outer joint member 2 and the inner joint member 3, and rotates at a constant speed between the two axes. Will be communicated.

  A female spline (spline includes serration; the same applies hereinafter) 16 is formed in the inner diameter hole 17 of the inner joint member 3, and a male spline 19 formed at the end of the intermediate shaft 12 is fitted to the female spline 16. , And are connected so that torque can be transmitted. The inner joint member 3 and the intermediate shaft 12 are positioned in the axial direction by a retaining ring 18.

  Boots 13 are mounted on the outer periphery of the outer joint member 2 and the outer periphery of the shaft 12 connected to the inner joint member 3, and both ends of the boot 13 are fastened and fixed by boot bands 14 and 15. Grease as a lubricant is sealed inside the joint covered with the boot 13.

  A stem portion 20 is integrally formed at the bottom of the mouth portion 2a of the outer joint member 2. The stem portion 20 has a male spline 21 fitted to a hub wheel (not shown) to which a driving wheel is attached and a fastening screw portion. 22 is formed.

  FIG. 3 is an enlarged cross-sectional view of the ball and track groove of FIG. As shown in FIG. 3, the ball 4 is in angular contact with the track groove 6 of the outer joint member 2 at two points C12 and C13, and is in angular contact with the track groove 7 of the inner joint member 3 at two points C15 and C16. . The angle (contact angle α) formed by a straight line passing through the ball center O5 and the contact points C12, C13, C15, C16 and a straight line passing through the ball center O5 and the joint center O is preferably set to 30 ° or more.

The eight ball type fixed type constant velocity universal joint 1 of the present embodiment is a ratio r1 of the pitch circle diameter (PCD _BALL ) and the ball diameter (D _BALL ) of the ball 4 with reference to FIG. 1 and FIG. = PCD _BALL / D _BALL ) is set within the range of 3.3 ≦ r1 ≦ 5.0, preferably 3.5 ≦ r1 ≦ 5.0. Here, the pitch circle diameter (PCD _BALL ) of the ball 4 is twice the size of the PCR (PCD _BALL = 2 × PCR). The length of the line segment connecting the center of curvature A of the track groove 6 of the outer joint member 2 and the center O5 of the ball 4, and the length of the line segment connecting the center of curvature B of the track groove 7 of the inner joint member 3 and the center O5 of the ball 4 Are respectively PCR, and both are equal. The ratio r2 (= D _OUTER / PCD _SERR ) between the outer diameter (D _OUTER ) of the outer joint member 2 and the pitch circle diameter (PCD _SERR ) of the female spline 16 of the inner diameter hole 17 of the inner joint member 2 is 2.5. It is set to a value within the range of ≦ r2 ≦ 3.5. Therefore, it has strength, load capacity and durability equal to or higher than those of conventional joints (6-ball type fixed constant velocity universal joints), and the outer diameter is compact.

  The overall configuration of the fixed type constant velocity universal joint 1 of the present embodiment is as described above, but the feature of the fixed type constant velocity universal joint 1 of the present embodiment is that the pocket 5a of the cage 5 and the torque transmission ball 4 are The clearance between the pockets is up to the positive clearance in the ball movement area at the normal angle, and the negative clearance is set in the area other than the ball movement area at the normal angle. As a result, it is possible to realize a fixed type constant velocity universal joint in which abnormal noise (ball hitting sound) does not occur in the region where the operating angle of the joint is large and torque loss is small at the normal angle.

  Here, the common angle of the fixed type constant velocity universal joint 1 will be described. In the case of a drive shaft of an automobile, the normal angle is an operating angle generated in the fixed constant velocity universal joint 1 of the front drive shaft when the steering is straight in a vehicle where two passengers are on a horizontal and flat road surface. Say. The service angle is usually determined between about 2 ° and 15 ° according to the design conditions for each vehicle type. Automobiles are broadly classified into sedan passenger cars and SUVs (sports multipurpose vehicles). A sedan passenger car usually has a common angle of about 3 ° to 6 °. The SUV is a vehicle having a high vehicle height including a van and a pickup truck, and usually has a common angle of about 6 ° to 12 °.

The pocket clearance between the pocket 5a of the cage 5 and the ball 4 will be described with reference to FIG. FIG. 8 is a longitudinal sectional view of the cage 5. The cage 5 is provided with eight pockets 5a in the circumferential direction defined by the pillar portion 5b. The surface facing the axial direction of the pocket 5a is a pocket side surface 5a1 that holds the ball 4, and the axial dimension between the pocket side surfaces 5a1 and 5a1 is N. The initial pocket clearance with the diameter (D _BALL ) of the ball 4 indicated by a two-dot chain line is expressed by the following equation.
Initial pocket clearance = Axial dimension between side surfaces 5a1, 5a1 of cage 5 N-ball diameter (D _BALL )
The initial pocket clearance is a positive clearance when the ball diameter (D _BALL ) is smaller than the axial dimension N, and conversely, a negative clearance when the ball diameter (D _BALL ) is larger than the axial dimension N.
In the present specification and claims, the initial pocket clearance between the cage pocket and the torque transmitting ball is used in the above sense. Also, the initial pocket clearance up to a negative clearance means a negative clearance including zero clearance. In the following description, the initial pocket clearance is simply abbreviated as pocket clearance. In FIG. 8, the pocket clearance (correct clearance) is exaggerated for easy understanding.

First, the examination result and knowledge of the development process up to this embodiment will be described with reference to FIGS.
(1) Verification of transmission efficiency in the normal angle In order to investigate the transmission efficiency in the normal angle region, an experiment was conducted using an EBJ82M manufactured by NTN as an 8-ball Zeppa constant velocity universal joint (the same applies to the subsequent experiments). Samples with various pocket clearances were manufactured, and torque loss rates were determined for operating angles of 4 °, 6 °, and 8 °. The pocket side surface 5a1 of the cage 5 in this sample has a flat conventional shape with no irregularities. The experimental results are shown in FIG. As a result, it was confirmed that the torque loss rate was increased when the pocket clearance amount was −10 μm or less.

(2) Verification of abnormal noise in high operating angle range Samples with various values were produced until the pocket clearance was correct, and experiments were conducted at operating angles of 35 ° and 40 °. The experimental results are shown in FIG. As a result, it was found that when the pocket clearance amount was +30 μm or more, an abnormal noise could be heard even at a position away from the joint. Since the wear of the pocket portion progresses over a long period of use, the initial value of the pocket clearance that anticipates deterioration over time is generally set to a negative clearance or zero. For this reason, it is not easy to reduce the torque loss rate.

(3) Analysis of abnormal noise generation mechanism The relationship between pocket clearance and transmission loss rate and the relationship between pocket clearance and abnormal noise were confirmed. Next, the mechanism of abnormal noise generation was investigated. FIG. 6A shows a state where the joint has a large operating angle θ. In the drawing, a broken line L1 is a locus of a contact point between the track groove 6 of the outer joint member 2 and the ball 4, and a broken line L2 is a locus of a contact point between the track groove 7 of the inner joint member 3 and the ball 4. As shown in FIG. 2, the phase angle at the top dead center in FIG. 6A is 0 °, and as shown in FIG. 2, 45 °, 90 °, 135 ° 180 ° 225 °, 270 °, 315 °, 360 ° To do. FIG. 7 is an analysis result showing variation in pocket load during one rotation of the joint when the joint transmits rotational torque at an operating angle of 40 °. The horizontal axis of FIG. 7 shows the phase angle during one rotation of the joint of any one ball 4 and pocket 5a, and the vertical axis shows the value obtained by dividing the pocket loads P5 and P6 by the load PN in the rotational torque transmission direction. Indicates the dimensioned value. As shown in FIG. 6B, the pocket load P5 is a force by which the ball 4 pushes the cage 5 toward the opening side of the outer joint member 2, and the pocket load P6 is held by the ball 4 behind the outer joint member 2. This is the force that pushes the vessel 5.

  The phase angle surrounded by a circle in FIG. 7 indicates a portion where the direction of the pocket load is reversed, and it is considered that the hitting sound of the ball is generated at such a phase angle. As shown in the figure, it was confirmed that the pocket load was reversed when the phase angle was about 30 °, 60 °, and 180 °. In this analysis, the pocket clearance was 10 μm.

(4) Analysis of the movement trajectory of the ball in the pocket When the joint takes an operating angle, the ball 4 slides in the radial direction and the circumferential direction of the cage 5 in the pocket 5 a of the cage 5. As shown in FIG. 8, the sliding in the circumferential direction (arrow h in FIG. 8) is that the ball 4 slides from the circumferential center of the pocket 5a so as to approach the column portion 5b. In this circumferential sliding, when the operating angle is taken, the outer joint member 2 and the inner joint member 3 are obliquely crossed, so that contact points C12 and C13 between the track grooves 6 and 7 adjacent to the circumferential direction and the ball 4 are obtained. Further, the circumferential interval between C15 and C16 (see FIG. 3) changes, and this causes the ball 4 restrained by the track grooves 6 and 7 to move in the circumferential direction with respect to the pocket 5a.

  On the other hand, the radial sliding (arrow g in FIG. 8) within the pocket 5a of the ball 4 is caused by the track offset amount f1 (see FIG. 1). As shown in FIG. 6A, when the operating angle θ is taken, the top dead center ball 4 moves to the opening side of the outer joint member 2 and the bottom dead center ball 4 moves to the outer joint member 2. Move to the back. Since the track offset amount f1 is provided, the track grooves 6 and 7 of the outer joint member 2 and the inner joint member 3 are formed so that the groove depth is deeper on the opening side and shallower toward the back side. Therefore, the ball 4 that has moved to the opening side of the outer joint member 2 moves to the outer side in the radial direction, and the ball 4 that has moved to the inner side of the outer joint member 2 moves to the inner side in the radial direction. In this way, the ball 4 moves in the radial direction depending on the axial position of the track grooves 6 and 7 in contact with the ball 4.

  As described above, the ball 4 slides in the radial direction and the circumferential direction of the cage 5 in the pocket 5a of the cage 5, and the mechanism of the movement trajectory of the ball 4 in the pocket 5a that aggregates this motion is analyzed. . FIG. 9 shows the result of the mechanism analysis. During one rotation of the joint, the ball 4 (not shown) moves so as to draw a figure 8 on the pocket side surface 5a1, and moves larger as the operating angle increases. FIG. 9 mainly shows the movement trajectory of a normal operating angle (operating angle 6 °) where torque loss is to be reduced and a high operating angle (operating angle 40 °) that may cause abnormal noise (ball hitting sound).

  The circumferential length of the pocket 5a of the cage 5 is set based on the assembly angle (about 65 °) required for ball assembly during assembly of the joint. This built-in angle is larger than the maximum operating angle (about 47 °) in the joint operating state. Since the pocket 5a has such a length in the circumferential direction, in the case of NTN EBJ82M, the ball 4 has a working width of about 1 mm from the central portion of the pocket side surface 5a1 to the left and right at a working angle (operating angle 6 °). e with a high operating angle (operating angle 40 °) and a moving width f of about 0.3 mm.

(5) New idea In consideration of comparing FIG. 7 and FIG. 9 described above, the positions of the balls 4 near the phase angles of 30 °, 60 °, and 180 ° that are considered to generate abnormal noise at high operating angles are as follows: The position of the ball 4 at the service angle (operating angle 6 °) that is frequently used and that is close to the inner diameter side and the outer diameter side deviated from the central portion of the pocket side surface 5a1 and for which torque loss is to be reduced most is described above. It has been noted that the movement width e remains in the vicinity of the central portion of the pocket side surface 5a1 even if about ± 1 mm is taken into account. With this attention, the present embodiment has been reached through a new idea of setting a preferred pocket clearance for each ball movement region at the normal angle and the high operating angle in the same pocket side surface 5a1 of the cage 5.

  The pocket clearance between the pocket 5a (pocket side surface 5a1) of the cage 5 and the ball 4 which is a feature of the fixed type constant velocity universal joint 1 of the present embodiment is up to the normal clearance in the ball movement region at the normal angle, and A specific configuration in which the negative clearance is set in the area other than the ball movement area at the normal angle will be described with reference to FIGS.

  FIG. 10A is a front view of the cage alone, and FIG. 10B is a perspective view of the cage alone. The retainer 5 has the spherical outer peripheral surface 10 and the spherical inner peripheral surface 11 as described above, and is provided with eight pockets 5a in the circumferential direction defined by the column portion 5b. A pocket side surface 5 a 1 facing the axial direction of the pocket 5 a is a surface for holding the ball 4. The present embodiment is characterized by the shape of the pocket side surface 5a1.

  A specific shape of the pocket side surface 5a1 will be described with reference to FIGS. 11 (a) to 11 (c). 11 (a) is a cross-sectional view taken along line GG in FIG. 10 (a), FIG. 11 (b) is an enlarged view of portion I in FIG. 10 (a), and FIG. (B) It is the fragmentary sectional view seen by the arrow JJ of a figure. As shown in the figure, a band-shaped recess 30 is formed in the center of the pocket side surface 5a1 in the circumferential direction. The depth a of the recess 30 shown in FIG. 11C is about 5 to 30 μm. However, in FIG. 11C, the depth a of the recess 30 is exaggerated for easy understanding. Since the depth “a” of the recess 30 is as shallow as about 5 to 30 μm, the dimensions are such that the ball 4 can come into contact with the bottom of the recess 30. Similarly, in the respective forms and modifications of the recesses described later, the dimensions are such that the ball 4 can contact the bottom.

  The length b of the recess 30 shown in FIG. 11 (b) is about 2 to 3 mm in consideration of the movement width e at the normal angle, the width c is about 1 to 2 mm, and when the joint operates at the normal angle. The movement trajectory of the ball 4 is included. Thereby, the initial pocket clearance can be reliably set to the correct clearance in the ball movement region at the normal angle. In addition, since the band-shaped concave portion 30 is formed in the central portion of the pocket side surface 5a1 in the circumferential direction, the initial pocket clearance can be set with high processing efficiency.

  In the present embodiment, the recess 30 is provided on one side of the pocket side surface 5 a 1 that faces the cage 5 in the axial direction. Since the recess 30 is provided, in the ball movement region at the normal angle, the dimension obtained by adding the depth a of the recess 30 to the distance between the pocket side surfaces 5a1, 5a1 is the axial dimension N shown in FIG. The pocket clearance is the correct clearance. Surfaces other than the concave portion 30 of the pocket side surface 5a1 maintain the distance between the two side surfaces 5a1, 5a1 facing each other so as to obtain a pocket clearance equivalent to the conventional case, that is, a negative clearance.

  In the present embodiment, the concave portion 30 is provided on one side of the pocket side surface 5a1, but the present invention is not limited to this, and the concave portion 30 may be provided on both side pocket side surfaces 5a1. The means for forming the recess 30 may be machining such as cutting or grinding, or may be cold plastic working or electric discharge machining. Although the length b is about 2 to 3 mm and the width c is about 1 to 2 mm as the dimensions of the recess 30, this dimension is appropriately increased or decreased depending on the size of the joint.

  Since the pocket side surface 5a1 is configured as described above, the pocket clearance is positive in the ball movement region at the frequently used operating angle, and is negative in the ball movement region at the high operating angle. Thus, a preferable pocket clearance can be set for each ball movement region in the normal angle and the high operating angle in the same pocket side surface 5a1. As a result, it is possible to realize the fixed constant velocity universal joint 1 that can reliably reduce the torque loss rate in the ball movement region at the normal angle and that does not generate any abnormal noise in the ball movement region at the high operating angle. As a more specific effect, idling vibration can be improved by reducing the bending torque, and the movement of the ball is smoothed and the frictional force is reduced, so that heat generation during joint operation is reduced and the durability life is improved.

12A to 12E show various forms of recesses on the side surfaces of the pockets. FIG. 12A is a vertical cross-sectional view of the cage taken along line KK in FIG. 10A, and FIGS. 12B to 12E show L in FIG. 12A. It is an enlarged view of a part. Figure 12 recess 30 ₁ shown in (b) is for the cross-sectional shape of the recess 30 of FIG. 11 described above (b) and FIG. 11 (c) was in an arc-shaped curvature radius r1, 12 (c) The recess 30 ₂ shown in FIG. ₂ has a cross-sectional shape formed by a tapered surface with an inclination angle β1. Thereby, it is possible to smoothly connect the ball movement region at the normal angle and the region other than this region.

Pocket side 5a1 shown in FIG. 12 (d) is formed by the concave 30 ₃ in cross-section of the cage 5, the radial overall width of the pocket side surface 5a1 is formed in an arc-shaped curvature radius r2. Pocket side 5a1 shown in FIG. 12 (e) is formed by the concave 30 ₄ in cross-section of the cage 5, the radial overall width of the pocket side surface 5a1 is formed in the tapered surface of the inclination angle .beta.2. Thereby, the whole pocket side surface 5a1 can be processed at once by mechanical processing such as cutting or grinding, cold plastic processing, electric discharge processing, or the like. In addition, it is possible to smooth the change in the amount of pocket clearance between the ball movement region at the normal angle and the region other than this region. The lengths of the concave surfaces 30 ₃ and 30 _{4 in} the circumferential direction are set to appropriate dimensions of about 2 to 3 mm or more. The concave surfaces 30 ₃ and 30 ₄ also have a depth of about 5 to 30 μm, and the pocket clearance in the ball movement area at the frequently used service angle is a positive clearance, and the negative clearance in the ball movement area at a high operating angle. . As a result, it is possible to realize the fixed type constant velocity universal joint 1 in which the torque loss rate can be reliably reduced in the ball movement region at the normal angle and no abnormal noise is generated in the ball movement region at the high operating angle.

As described above, since the depths of the recesses 30 ₁ , 30 ₂ , and the concave surfaces 30 ₃ , 30 ₄ are extremely shallow, about 5 to 30 μm, the radii of curvature r1, r2 are correspondingly large, and the inclination angle β1. , Β2 is correspondingly small. The same applies to the curvature radius r3 and the inclination angle β3 of the modified example described later.

FIG. 13A to FIG. 13C show a first modification of the concave portion on the side surface of the pocket. 13A is a cross-sectional view taken along the line GG in FIG. 10A, and FIG. 13B is an enlarged view of a portion I in FIG. 13A. ) Is a partial cross-sectional view taken along line JJ in FIG. As shown, the recess 30 ₅ of this modification is formed in a narrow band width in the radial direction in the center of the pocket side surface 5a1 (width of about 1 mm), the spherical outer peripheral spherical inner peripheral surface 11 of the cage 5 It extends to the surface 10. As shown in FIG. 13 (c), the cross-sectional shape of the concave portion 30 ₅ is an arcuate curvature radius r3.

In the first embodiment described above, the length b of the concave portion 30 is set to about 2 to 3 mm in consideration of the movement width e (about ± 1 mm) of the ball 4 at the normal angle (operating angle 6 °). However, when the position of the ball 4 on the pocket side surface 5a1 at the normal angle was observed, it was confirmed that the ball 4 remained in a well-sitting place on the pocket side surface 5a1. Based on this finding, as a result of thinking further form of recesses recalled this modification is formed into a narrow recess 30 ₅ width over the radial overall width in the central portion of the pocket side surface 5a1 strip (width of about 1mm) . Also in this case, the pocket clearance of the portion used at the normal angle is a positive clearance, and the portion used at the high operating angle is basically a negative clearance. The high operating angle balls 4 a recess 30 ₅ of the strip during moves, it was confirmed that not lead to abnormal sound because of the narrow band width. Also in this modified example, the ball movement region at the normal angle can surely reduce the torque loss rate, and it is possible to realize the fixed type constant velocity universal joint 1 that does not generate any abnormal noise even at a high operating angle. Further, if the recess 30 ₅ of this modification, can simultaneously molded during shaving pocket side 5a1, productivity is good and the manufacturing cost can be suppressed.

  Since other configurations are the same as those in the first embodiment, parts having the same functions are denoted by the same reference numerals (excluding subscripts), and the description in the first embodiment is applied mutatis mutandis. The description is omitted.

FIG. 14A to FIG. 14B show a second modification of the concave portion on the side surface of the pocket. 14A is an enlarged view of a portion I in FIG. 11A, and FIG. 14B is a partial cross-sectional view taken along line JJ in FIG. 14A. As shown in the figure, the concave portion 30 ₆ of the present modification is formed in a band shape (about 1 mm wide) in the radial direction at the central portion of the pocket side surface 5a1 as in the first modification. It extends from the inner peripheral surface 11 to the spherical outer peripheral surface 10. As shown in FIG. 14 (b), the cross-sectional shape of the recess 30 ₆ are formed in the tapered surface of the inclination angle .beta.3. Although this point is different from the first modified example, other configurations and operations are the same as those of the first modified example. Therefore, parts having similar functions are denoted by the same reference numerals (excluding subscripts). The contents described in the first modification are applied mutatis mutandis, and the description is omitted.

Next, the fixed type constant velocity universal joint which concerns on 2nd Embodiment is demonstrated based on FIG. 15 and FIG. 15 is a partial vertical cross-sectional view of a fixed type constant velocity universal joint, and FIG. 16 is a side view taken along line MM in FIG. Fixed type constant velocity universal joint 1 of _the present embodiment is a Tsueppa type constant velocity universal joint using six balls. Although the point that six balls are used is different from that of the first embodiment, the other configurations are the same as those of the first embodiment. Therefore, parts having the same functions are denoted by the same reference numerals (subscripts). The contents described in the first embodiment are applied mutatis mutandis, and only the main points will be described.

Fixed type constant velocity universal joint 1 of _the present embodiment, the outer joint member 2 _1, inner joint member 3 _1, the ball 4 ₁ and the retainer 5 ₁ mainly configured. The outer joint member 2 ₁ a spherical inner circumferential surface 8 track grooves 6 ₁ six curved to ₁ are formed equiangularly, and along the axial direction. The spherical outer peripheral surface 9 ₁ of the inner joint member 3 _1, curved track grooves 7 ₁ of the outer joint member 2 ₁ of the track grooves ₆₁ and six the opposing equiangularly, and along the axial direction Is formed. Six balls 4 ₁ for transmitting torque between the track grooves 7 ₁ of the outer joint member 2 ₁ of the track grooves ₆₁ and the inner joint member 3 ₁ is incorporated one by one. Between the outer joint member 2 spherical inner peripheral surface ₈₁ of ₁ and the inner joint member 3 ₁ of the spherical outer peripheral surface 9 _1, the cage 5 ₁ is arranged to hold the ball 4 _1. Each spherical outer peripheral surface 10 ₁ of the cage 5 ₁ The spherical inner peripheral surface ₈₁ of the outer joint member 2 _1, the cage 5 ₁ of the spherical inner peripheral surface 11 ₁ and the spherical outer peripheral surface 9 ₁ of the inner joint member 3 ₁ It is mated.

The outer joint member 2 ₁ a spherical inner peripheral surface ₈₁ and the inner joint member 3 ₁ of the center of curvature of the spherical outer peripheral surface 9 ₁ is formed on the center O of the joint respectively. In contrast, the center of curvature A ₁ of the outer joint member 2 ₁ a curved track grooves _61, the center of curvature B ₁ of the inner joint member 3 ₁ curved track grooves 7 _1, the center O of the joint On the other hand, it is offset by an equal distance f2 on the opposite side in the axial direction. Thus, if the joint forms an operating angle, the balls 4 ₁ an angle both the axis of the outer joint member 2 ₁ and the inner joint member 3 ₁ forms on a plane second - is always guided, constant velocity between two axes Rotation is transmitted to.

The cage 5 ₁ 6 pockets 5a ₁ in the circumferential direction is provided. A pocket side surface 5a1 ₁ facing the axial direction of the pocket 5a ₁ is a surface for holding the ball 4 ₁ . Although not shown, it is previously present embodiment, a first embodiment and similar concave or concave and its modification is formed in a pocket side 5a1 _1. For this reason, the pocket clearance in the ball movement region at the frequently used operating angle is a positive clearance, and the ball movement region at a high operating angle is a negative clearance. As a result, the ball moving region in common angle conventional angle can reliably reduce the torque loss ratio, and it becomes possible to realize a fixed type constant velocity universal joint 1 ₁ occurrence is not of noise at high operating angle.

A fixed type constant velocity universal joint according to a third embodiment of the present invention will be described with reference to FIG. FIG. 17 is a partial longitudinal sectional view of a fixed type constant velocity universal joint. Fixed type constant velocity universal joint 1 ₂ of the present embodiment is undercut-free type constant velocity universal joint using six balls. Although it differs from the first embodiment in that six balls are used and there is no undercut in the track groove, the other configurations are the same as those in the first embodiment, so the same function is applied to parts having similar functions. Only the main points will be described using the contents described in the first embodiment mutatis mutandis.

Fixed type constant velocity universal joint 1 ₂ of the present embodiment, the outer joint member 2 _2, inner joint member 3 _2, the ball 4 ₂ and the retainer 5 ₂ and main structure. The outer joint member 2 _{and second} spherical inner peripheral surface ₈₂ six curved track grooves 6 ₂ in are formed equiangularly, and along the axial direction. The inner joint member 3 _{and second} spherical outer peripheral surface 9 _2, curved track grooves 7 ₂ of the outer joint member 2 _{and second} track grooves 6 ₂ and 6 present the opposing equiangularly, and along the axial direction Is formed. Curved track grooves 6 ₂ of the outer joint member 2 ₂ is provided with a linear track groove portion 6 _2S on the opening side of the outer joint member 2 _2. On the other hand, the curved track groove 7 ₂ of the inner joint member 3 ₂ includes a linear track groove portion 7 _2S on the back side of the outer joint member 2 ₂ . Six balls 4 ₂ for transmitting torque between the outer joint member 2 and _second track grooves 6 ₂ and the inner joint member 3 and _second track grooves 7 ₂ is incorporated one by one. Between the outer joint member 2 _{and second} spherical inner peripheral surface ₈₂ and the inner joint member 3 _{and second} spherical outer peripheral surface 9 _2, the cage 5 ₂ are arranged to hold the ball 4 _2. Each spherical outer peripheral surface 10 ₂ of the cage 5 ₂ and the outer joint member 2 _{and second} spherical inner peripheral surface _82, the spherical inner peripheral surface 11 ₂ of the cage 5 ₂ The inner joint member 3 _{and second} spherical outer peripheral surface 9 ₂ It is mated.

The center of curvature C ₂ of the cage 5 ₂ spherical outer peripheral surface 10 ₂ and the outer joint member 2 _{and second} spherical inner peripheral surface _82, the cage 5 ₂ spherical inner peripheral surface 11 ₂ and the inner joint member 3 _{and second} spherical outer periphery center of curvature D ₂ surface 9 ₂ are equidistant f4 axially offset opposite to the center O of the joint. Further, the center of curvature A ₂ of the outer joint member 2 _{and second} curved track grooves 6 _2, the center of curvature B ₂ of the inner joint member 3 _{and second} curved track grooves 7 _2, the axis with respect to the center O of the joint Equal distance f3 is offset on the opposite side. Even in the fixed type constant velocity universal joint 1 ₂ of the present embodiment, when the joint forms an operating angle, the balls 4 the angle both the axis of the outer joint member 2 ₂ and the inner joint member 3 ₂ forms on a plane second - ₂ is always guided, and rotation is transmitted at a constant speed between the two axes.

Fixed type constant velocity universal joint 1 ₂ of the present embodiment, curved track grooves 6 _2, 7 _2, since each comprise straight track grooves 6 _2S, 7 _2S a part thereof, undercuts There will be no track grooves. The fixed type constant velocity universal joint 1 ₂ may be due to the presence of linear track grooves 6 _2S on the opening side of the outer joint member 2 _2, it corresponds to a larger operating angle.

The cage 5 ₂ 6 pockets 5a ₂ in the circumferential direction are provided. Pocket side surfaces 5a1 ₂ axially opposite the pockets 5a ₂ is a surface for holding the ball 4 _2. Although not shown, it is previously present embodiment, the first embodiment and similar concave or concave and its modification is formed in a pocket side 5a1 _2. For this reason, the pocket clearance in the ball movement region at the frequently used operating angle is a positive clearance, and the ball movement region at a high operating angle is a negative clearance. As a result, the ball moving region in common angle can reliably reduce the torque loss ratio, and also enables the generation is not a fixed constant velocity universal joint 1 ₂ realization of noise at high operating angle.

In actual driving conditions of automobiles, on sharply curved roads and intersections, the operating angle generated in the fixed type constant velocity universal joint is larger than the above-mentioned normal angle. In joints 1, 1 ₁ and 1 ₂ , the frequency of use at large operating angles such as sharply curved roads and intersections is low, so by improving joint efficiency (reducing torque loss rate) in the range of regular angles, Overall, joint efficiency can be improved.

  The present invention is not limited to the above-described embodiments, and can of course be implemented in various forms without departing from the scope of the present invention. The scope of the present invention is not limited to patents. It includes the equivalent meanings recited in the claims and the equivalents recited in the claims, and all modifications within the scope.

1 fixed type constant velocity universal joint 2 outer joint member 3 inner joint member 4 torque transmitting ball 5 cage 5a pocket 5a1 pocket side surface 6 track groove 7 track groove 8 spherical inner peripheral surface 9 spherical outer peripheral surface 10 spherical outer peripheral surface 11 spherical inner peripheral surface Surface 12 Intermediate shaft 13 Boot 30 Recess A Center of curvature B Center of curvature C ₂ Center of curvature D ₂ Center of curvature D _BALL Ball diameter N Axial dimension O Joint center f1 Offset amount f2 Offset amount f3 Offset amount

Claims (8)

An outer joint member in which a plurality of curved track grooves extending in the axial direction are formed on the spherical inner peripheral surface; an inner joint member in which a plurality of curved track grooves extending in the axial direction are formed on the spherical outer peripheral surface; A plurality of torque transmitting balls disposed between the track grooves of the outer joint member and the corresponding track grooves of the inner joint member, and holding the torque transmitting balls in the pockets and A cage having a spherical outer peripheral surface and a spherical inner peripheral surface, which are respectively fitted to a peripheral surface and a spherical outer peripheral surface of the inner joint member, and a curvature center of a curved track groove of the outer joint member; In the fixed type constant velocity universal joint where the center of curvature of the curved track groove is offset equidistant to the opposite side in the axial direction with respect to the joint center,
Of the pair of pocket side surfaces facing in the axial direction of the pocket, a recess is formed in the central portion in the circumferential direction of at least one pocket side surface, and this recess includes the movement trajectory of the torque transmitting ball at a normal angle,
Of the initial pocket clearance between the cage pocket and the torque transmitting ball, the initial pocket clearance of the ball movement region at the service angle is set in the recess,
The initial pocket clearance between the cage pocket and the torque transmitting ball is up to the normal clearance in the ball movement region at the normal angle, and is a negative clearance in the region other than the ball movement region at the normal angle. Fixed constant velocity universal joint. The fixed type constant velocity universal joint according to claim 1 , wherein the concave portion has a band shape in a circumferential direction of the cage. 2. The fixed type constant velocity universal joint according to claim 1 , wherein the concave portion has a belt shape in a radial direction of the cage and extends from the spherical inner peripheral surface of the cage to the spherical outer peripheral surface. The fixed constant velocity universal joint according to any one of claims 1 to 3 , wherein a cross-sectional shape of the concave portion is an arc shape. The fixed constant velocity universal joint according to any one of claims 1 to 3 , wherein a cross-sectional shape of the recess is a tapered surface.   The fixed type constant velocity universal joint according to claim 2, wherein the side surface of the pocket is formed as a concave surface in a cross section of the cage. The fixed constant velocity universal joint according to claim 6 , wherein a cross-sectional shape of the concave surface is an arc shape. The fixed type constant velocity universal joint according to claim 6 , wherein a cross-sectional shape of the concave surface is a tapered surface.

Images